My sexual preferences have changed. I identified as straight-and bordering on homophobic when I was younger. Then-I fell in love with a woman.
Now I identify as bi.
As for anal-my "circumstantially he might be bi" friend has no use for anal (either giving or receiving) and a friend who LOVES giving and receiving anal is straight as a board.
I say-it's good that you are interested in learning more about yourself-be gentle with other people's feelings as you explore.